<template>
  <div class="container">
    <!-- 固定导航 -->
    <van-nav-bar
      fixed
      left-arrow
      @click-left="$router.back()"
      title="AIPoPo"
    ></van-nav-bar>

    <!-- 聊天主体区域 -->
    <div class="chat-list">
      <div v-for="(obj, index) in list" :key="index">
        <!-- 左侧是机器人 -->
        <div class="chat-item left" v-if="obj.name !== 'me'">
          <van-image
            fit="cover"
            round
            src="https://img.yzcdn.cn/vant/cat.jpeg"
          />
          <div class="chat-pao">{{ obj.msg }}</div>
        </div>

        <!-- 右侧是当前用户 -->
        <div class="chat-item right" v-else>
          <div class="chat-pao">{{ obj.msg }}</div>
          <van-image fit="cover" round :src="$store.state.userPhoto" />
        </div>
      </div>
    </div>

    <!-- 对话区域 -->
    <div class="reply-container van-hairline--top">
      <van-field v-model="word" placeholder="说点什么...">
        <template #button>
          <span style="font-size: 12px; color: #999" @click="sendFn">提交</span>
        </template>
      </van-field>
    </div>
  </div>
</template>

<script>
import { io } from "socket.io-client";
import { getToken } from "@/utils/token.js";
export default {
  name: "Chat",
  data() {
    return {
      word: "", //输入框内容
      list: [
        // 所有的聊天消息
        //只根据name属性，既可判断出这个消息应该渲染到左侧还是右侧
        { name: "xs", msg: "hi,你好。" },
        { name: "me", msg: "hello word" },
      ],
      socket: null, //客户端和服务器端建立链接的socket对象
      // imgList: [],
    };
  },
  // props: {
  //   imgList: [], //用户头像信息
  // },
  created() {
    // eventBus.$on("imgList");
    // console.log(this.imgList);
    // this.$bus.$on("imgList", (value) => {
    //   console.log(value);
    // });
    // 注意：io是建立socket链接，和axios没有关系
    this.socket = io("http://geek.itheima.net", {
      query: {
        token: getToken(),
      },
      transports: ["websocket"],
    });
    // 测试是否建立链接成功
    this.socket.on("connect", () => {
      console.log("成功");
    });
    // 接收后端传回来的消息
    this.socket.on("message", (obj) => {
      this.list.push({
        // 立刻组织相同字段对象放到数组里-》v-for更新
        name: "xs",
        msg: obj.msg,
      });

      // 最后一条聊天消息滚动到屏幕范围
      // 数据变化-》DOM更新是异步的，所以获取到的是上一条的DIV
      this.$nextTick(() => {
        const theDiv = document.querySelector(".chat-list>div:last-child");
        // console.log(theDiv);
        theDiv.scrollIntoView({
          behavior: "smooth",
        });
      });
    });
  },
  mounted() {},
  methods: {
    // 点击发送按钮事件
    sendFn() {
      if (this.word.trim().length === 0) return;
      // 用socket链接对象.emit('后端接收消息的事件名'，'值')
      this.socket.emit("message", {
        msg: this.word,
        timestamp: new Date().getTime(),
      });
      // 把消息显示到页面上
      this.list.push({
        msg: this.word,
        name: "me",
      });

      this.$nextTick(() => {
        const theDiv = document.querySelector(".chat-list>div:last-child");
        // console.log(theDiv);
        theDiv.scrollIntoView({
          behavior: "smooth",
        });
      });

      // 清空输入框
      this.word = "";
    },
  },
  destroyed() {
    this.socket.close();
    this.socket = null;
  },
};
</script>

<style lang="less" scoped>
// 头部导航栏样式
.van-nav-bar {
  background-color: #575b60;
}
/deep/ .van-nav-bar__title,
/deep/.van-nav-bar__arrow {
  color: #fff;
}

.container {
  height: 100%;
  width: 100%;
  position: absolute;
  left: 0;
  top: 0;
  box-sizing: border-box;
  background: #fafafa;
  padding: 46px 0 50px 0;
  .chat-list {
    height: 100%;
    overflow-y: scroll;
    .chat-item {
      padding: 10px;
      .van-image {
        vertical-align: top;
        width: 40px;
        height: 40px;
      }
      .chat-pao {
        vertical-align: top;
        display: inline-block;
        min-width: 40px;
        max-width: 70%;
        min-height: 40px;
        line-height: 38px;
        border: 0.5px solid #c2d9ea;
        border-radius: 4px;
        position: relative;
        padding: 0 10px;
        background-color: #e0effb;
        word-break: break-all;
        font-size: 14px;
        color: #333;
        &::before {
          content: "";
          width: 10px;
          height: 10px;
          position: absolute;
          top: 12px;
          border-top: 0.5px solid #c2d9ea;
          border-right: 0.5px solid #c2d9ea;
          background: #e0effb;
        }
      }
    }
  }
}
.chat-item.right {
  text-align: right;
  .chat-pao {
    margin-left: 0;
    margin-right: 15px;
    &::before {
      right: -6px;
      transform: rotate(45deg);
    }
  }
}
.chat-item.left {
  text-align: left;
  .chat-pao {
    margin-left: 15px;
    margin-right: 0;
    &::before {
      left: -5px;
      transform: rotate(-135deg);
    }
  }
}
.reply-container {
  position: fixed;
  left: 0;
  bottom: 0;
  height: 44px;
  width: 100%;
  background: #f5f5f5;
  z-index: 9999;
}
</style>